Flexible Packaging Materials Selection Guide: LDPE vs HDPE vs PP vs PA vs EVOH Compared
Selecting the right film structure is the single most consequential decision in flexible packaging procurement. Choose correctly and you get adequate shelf life, smooth machinability, and the lowest possible unit cost. Choose poorly and you face seal failures, product spoilage, or paying for barrier performance you never needed.Selecting the right film structure is the single most consequential decision in flexible packaging procurement. Choose correctly and you get adequate shelf life, smooth machinability, and the lowest possible unit cost. Choose poorly and you face seal failures, product spoilage, or paying for barrier performance you never needed.
This guide compares the core polymers used in flexible packaging — LDPE, HDPE, PP, PA (nylon), and EVOH — on the properties that matter in real purchasing decisions, and matches materials to common product categories.
Core Material Properties at a Glance
| Property | LDPE | HDPE | PP (cast/BOPP) | PA (Nylon 6) | EVOH (co-extruded) |
|---|---|---|---|---|---|
| Density (g/cm³) | 0.910–0.925 | 0.941–0.965 | 0.895–0.905 | 1.13 | 1.14–1.19 |
| Tensile strength (MPa) | 8–25 | 20–40 | 30–60 (BOPP) | 70–90 | 60–80 |
| Oxygen barrier (OTR, cc/m²·day·atm @25µm) | ~7,000+ | ~4,000 | ~3,000 | 30–80 | 0.01–0.6 |
| Moisture barrier (WVTR, g/m²·day) | Poor–moderate | Good | Moderate | Poor | Good |
| Puncture resistance | Good | Moderate | Moderate | Excellent | Brittle alone |
| Heat seal temp (°C) | 120–160 | 135–175 | 140–180 | Not sealable alone | N/A (co-ex layer) |
| Clarity | Good | Hazy | Excellent (BOPP) | Good | Excellent |
| Typical cost index* | 1.0 | 0.9 | 1.1 | 2.2 | 3.0 |
*Indexed relative cost of film per square meter at similar gauge.
Material Deep Dives
LDPE (Low-Density Polyethylene)
The workhorse of flexible packaging. LDPE dominates carrier bags, merchandise bags, garment packaging, and as the sealant layer in nearly every laminate structure.
- Strengths: Excellent heat-sealability and hot-tack, good tear resistance, easy processing, lowest processing temperature.
- Weaknesses: Poor oxygen barrier, low stiffness, poor high-temperature resistance (softens ~85°C).
- Best for: Shopping bags, gift bags, produce bags, frozen food packaging, liner films, sealant webs.
Spec tip: For heavy-duty carrier bags, specify LDPE/LLDPE blend (e.g., 70/30) — LLDPE boosts puncture and tear strength 30–50% at similar cost.
HDPE (High-Density Polyethylene)
Stiffer, stronger, and more moisture-resistant than LDPE at lower gauges.
- Strengths: High stiffness-to-weight ratio (allows gauge reduction of 20–30% vs LDPE), excellent moisture barrier, crisp printing surface, crackle "premium paper-like" hand feel.
- Weaknesses: Lower tear resistance, weaker seals, poor transparency.
- Best for: "Bag-for-life" carrier bags, thin grocery sacks, envelope windows, multi-wall liners.
Spec tip: HDPE at 25–30 µm often replaces LDPE at 40–50 µm for grocery bags — meaningful freight savings on container loads.
PP (Polypropylene)
Two forms matter: CPP (cast PP) for flexible, sealable films, and BOPP (biaxially oriented PP) for high-clarity, high-strength webs.
- Strengths: Excellent clarity and gloss (BOPP rivals cellophane), good moisture barrier, highest fatigue resistance for flex-cracking, heat resistance to ~110–120°C (hot-fill capable).
- Weaknesses: Poor low-temperature impact (brittle below ~0°C unless co-polymerized), moderate barrier.
- Best for: Snack food overwrap, bakery film, flower sleeves, gift wrapping film, lamination web for stand-up pouches.
PA / Nylon 6
PA is a structural and barrier layer, almost never used alone. In laminates (e.g., PA/PE, PET/PA/PE), it provides puncture resistance, toughness, and moderate oxygen barrier.
- Strengths: Best-in-class puncture and flex-crack resistance; survives vacuum packing of sharp or heavy products (cheese wedges, frozen seafood with shells).
- Weaknesses: Hygroscopic — barrier degrades sharply as RH rises (OTR at 80% RH can be 5–10× the dry value); not sealable alone.
- Best for: Vacuum bags, retort laminates (with PET), frozen food, bone-in meat packaging.
EVOH (Ethylene-Vinyl Alcohol Copolymer)
The premium oxygen barrier. EVOH is always co-extruded as a thin core layer (typically 3–8 µm) between PE or PP.
- Strengths: OTR as low as 0.01 cc/m²·day — 100–1,000× better than any polyolefin. Essential for oxygen-sensitive foods (coffee, nuts, processed meats, baby food).
- Weaknesses: Extremely moisture-sensitive (barrier collapses at high RH — must be sandwiched between moisture barriers); costly; thickness must be controlled for recyclability (PPWR context: keep under ~5% of total weight for mono-material classification).
- Best for: Modified-atmosphere packaging, high-barrier pouches, coffee valve bags, retort pouches.
Matching Materials to Products
| Product Category | Recommended Structure | Why |
|---|---|---|
| Apparel / retail carrier bags | LDPE or LDPE/LLDPE, 30–80 µm | Seal strength, printability, cost |
| Reusable grocery bags ("bag for life") | HDPE 25–30 µm or woven PP | Gauge economy, durability |
| Frozen vegetables / seafood | PA/PE or PA/EVOH/PE | Puncture + low-temp toughness |
| Coffee / nuts (high barrier) | PET/PE + EVOH, or metallized PET/PE | Oxygen barrier for aroma/oxidation |
| Snacks / confectionery | BOPP/CPP or BOPP/metPET/CPP | Clarity, moisture barrier, seal |
| Vacuum-packed cheese / meat | PA/PE 7-layer co-ex | O2 barrier + puncture + formability |
| Dry pet food (large format) | PET/PE or all-PE with EVOH | Drop strength + barrier at lower cost |
Key Specification Metrics to Put in Your RFQ
Don't order "PE film" — order against measurable criteria:
- OTR (ASTM D3985 / ISO 15105-2) — specify test conditions (23°C, 0% or 50% RH).
- WVTR (ASTM F1249) — critical for dry products in humid supply chains.
- Seal strength (ASTM F88) — target ≥15 N/15mm for pouches; specify hot-tack if line speeds exceed 40 m/min.
- Dart impact (ASTM D1709) and Elmendorf tear (ASTM D1922) — for bags handling rough logistics.
- Coefficient of friction (ASTM D1894) — critical for VFFS/HFFS machine runnability; specify 0.2–0.4 kinetic for most form-fill-seal lines.
Emerging Structures Worth Watching
Two developments are changing the material-selection equation for EU-bound packaging:
MDO-PE (Machine-Direction Oriented PE). Orienting PE film in the machine direction gives it stiffness and clarity approaching BOPP while remaining a mono-material PE — enabling high-performance stand-up pouches that qualify for Grade A recyclability. If you're migrating from PET/PE laminates, MDO-PE/PE structures are now the default recommendation.
BOPE (Biaxially Oriented PE). The next generation: fully biaxially oriented PE films combining BOPP-like optics and strength with mono-material recyclability. Still a premium-priced option (roughly 1.5–2× standard BOPP), but costs are falling as capacity scales.
Recycled-content PE. Food-grade rPE approved under EU 2022/1616 for mechanical recycling processes is becoming commercially available at scale — enabling true circular structures (rPE core + virgin sealant layer) that satisfy both PPWR recyclability and recycled-content mandates in one design.
Balancing Cost and Performance
Three rules from the factory floor:
- Don't over-barrier. If shelf life is 6 months and distribution is temperate, you likely don't need EVOH. Every unnecessary layer adds 15–40% material cost.
- Gauge optimization beats material switching. A well-designed 55 µm PE/LLDPE structure often outperforms a poorly specified 70 µm LDPE at lower cost.
- Mono-material structures now rival laminates for mid-barrier applications — and they cut EPR fees (see our EPR guide) and satisfy PPWR recyclability grading.
Need Help Specifying Your Film Structure?
LiHai Industrial engineers flexible packaging structures to your exact barrier, seal, and machine requirements — from single-layer carrier bags to 7-layer barrier laminates. We provide full test data with every quotation.
Send us your product specs and get a material recommendation plus free samples within 48 hours.
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Get a Quote →Published: October 2026 Tags: flexible packaging materials, LDPE vs HDPE vs PP, packaging film selection, EVOH barrier film, packaging material comparison